Apparatus for controlling fluid flow



Nov. 9, 1965 J. F. GRUNDMANN APPARATUS FOR CONTROLLING FLUID FLOW 2Sheets-Sheet 1 Original Filed Nov. 2

WATER SUPPLY I 4 2 I IIII w H/Q I! I I Y vv whmmvrw 1-111 THERMOSTATPOWER SOURCE FIG.

JOHN F. GRUNDMANN INVENTOR.

KENDRICK,SCHRAMM8|STOLZY ATTORNEYS.

United States Patent 3,216,623 AlPARATUS FOR CONTRDLLING FLUID FLOW JohnF. Grundmann, 651 S. Irena Ave, Redondo Beach, Calif.

Original application Nov. 2, 1961, Ser. No. 149,567, now Patent No.3,161,206, dated Dec. 15, 1964. Divided and this application Mar. 19,1963, Ser. No. 266,457

5 Claims. (Cl. 222146) This application is a division of co-pendingapplication Ser. No. 149,567, filed Nov. 2, 1961, by John F. Grundmannfor Method and Apparatus for Controlling Fluid Flow, now Patent No.3,161,206, dated Dec. 15, 1964.

This invention relates to the fluid mechanics art, and more particularlyto a method of and apparatus for controlling the flow of fluid.

Although the present invention will have application in a great manyfields and is not therefore to be limited to any particular oneincluding that described in this paragraph, it has been found especiallyuseful in the control of the circulation of hot water in coin-operatedvending machines for dispensing brewed coffee, brewed coffee beingdistinguished from coffee made by mixing a pulverized dehydrated coffeebean extract or instant coffee with hot water.

In such machines coffee is brewed from ground as, for example, in adripolator where hot water is passed through the grounds and the groundsthereafter separated from the coffee liquor.

Athough the present invention is especially applicable to a brewedcoffee vending machine, it is also applicable to an instant coffeevending machine. A problem does exist relative to providing water of auniform temperature in an instant automatic vending machine, thetemperature of the water being independent of the demand on the machine.That is, during coffee breaks in places of business, the machine demandmay be one cup per minute whereas the demand on the machine for aweekend may be zero. Due to the fact that water carrying tubingconnected from a heated supply tank to a dispensing valve, the valveitself, and other connected high heat conducting metal structures in themachine may be cold on a Monday morning, it would naturally follow thatthe first cup of coffee dispensed by the machine would likely be cold.Note will be taken that the number of calories in a single cup ofboiling water may be very small in comparison to the large heat capacityof the above-mentioned conducting metal structures.

The problem of maintaining dispensed coffee at a uniform temperatureregardless of demand exists in instant coffee vending machines, but thisproblem becomes more perplexing in brewed coffee blending machinesbecause hotter brewing water is required. For example, water at 200Fahrenheit is normally required, this temperature being only twelvedegrees below the boiling point of water. Still further, it will beappreciated that heat transfer is proportional to the difference intemperature of the water and the heat conducting metal structures withwhich it comes in contact, and water, of course, cannot be heated to atemperature greater than boiling uu'thout considerable difficulty.Hence, the drop in temperature attributable to a cold distributionsystem in a brewed coffee vending machine because the Water temperaturerequired for the former is higher.

It is to be noted that the present invention applies to both instantcoffee and brewed coffee vending machines, although the problem itsolves is accentuated in a brewed coffee vending machine. The relativeease with which instant coffee can be made is undeniable because mostconventional instant coffee powders do, in fact, dissolve in waterinstantaneously and further because the separation of grounds from thecoffee liquor is therefore not necessary. However, a substantial demandfor brewed coffee vending machines exists because of the undeniablydifferent flavors of brewed and instant coffees, if not for the reasonthat brewed coffee is better in quality than instant coffee.

In the prior art, a brewed coffee vending machine has been provided witha complicated electrically operated valve system and an electric motordriven centrifugal pump to circulate hot water continuously, i.e.twentyfour hours a day, through the above-mentioned structures includingthe tube connecting the water supply tank to the water dispensing valve,the Water dispensing valve itself and through other surrounding highlyconductive metal structures to keep them hot, so that the temperature ofthe coffee dispensed by the machine will not vary considerably or at allregardless of coffee demand.

The present invention overcomes the above-described and otherdisadvantages of the prior art by providing a method including the stepsof filling a closed piping loop having an upwardly extending input leg,a downwardly extending output leg, and a chamber connecting the lowerends of the legs with a fluid, heating fluid in the connecting chamber,and cooling fluid in the legs at different corresponding rates. Bycooling one leg of a hot water circulation system in an automatic brewedcoffee vending machine at a rate greater than the other, the density ofthe water in the one leg increases to a magnitude greater than that inthe other, and the requirement for circulation to keep the dispensingparts of the machine always at a relatively high temperature is met.Lighter water in the one leg rises, and heavier water in the other legfalls. The differential pressure across the closed piping loop to causecirculation is small; however, the same unquestionably has been found tobe adequate and without the requirements of the complicated andexpensive prior art valve system and circulation pump.

According to an outstanding feature of the present invention, apparatusis provided including a tank, an inverted U-shaped tube havingdownwardly extending legs connected to the tank at differentcorresponding positions, the legs being constructed in a manner suchthat one has a different heat loss than the other, and means to heat thetank. The construction of each leg in a manner such that one has a heatloss to the atmosphere different than the other may be achieved byproviding insulation for only one of the two legs. Thus, a strikingadvantage of this apparatus of the invention is that for a constantwater temperature in the tank, circulation in the tub increases as theambient temperature decreases because water in the leg not insulatedbecomes still heavier to increase the differential circulation pressure.Hence, in accordance with this advantage of the present invention,compensation for low and changing ambient temperatures is madeautomatically to keep the water dispensing valve, the tube connectedfrom the valve to the tank, and other highly conductive metal structuresconnected with or positioned adjacent thereto at a substantiallyconstant and at a relatively high temperature independent of ambienttemperature.

According to another feature of the invention, the insulated leg of thetube opens into the tank near the bottom thereof, e.g., at the center ofthe tank, the leg not insulated opens in to the tank near the top of it,e.g., at one side. In this manner, the differential pressure causingcirculation in the tube is increased not only by this leg spacing toprevent cold water escaping from the leg not insulated from entering theinsulated leg, but also by heating water in the tank at the bottomthereof and relying on the finite, albeit it small, differentialtemperab ture between water at the bottom and at the top of the tank.

A brewed coffee vending machine made in accordance with thepresent'invention may include several other new and improved componentparts or arrangements thereof or new and improved arrangements ofconventional parts as follows: dispensing means connected with the tubebetween the legs, a first check valve in one of the legs, the firstcheck valve being adapted to close when pressure in a portion of the oneleg between the first check valve and the dispensing means is greaterthan that in a portion of the one leg between the first check valve andthe tank, a second check valve in the other of the legs, the secondcheck valve being adapted to close when a diiferential of pressureacross it is of a predetermined magnitude regardless of whether or notthe water pressure thereabove in the other leg is higher or lower thanthe water pressure therebelow in the other leg, insulation surroundingonly a portion of the other leg of the tube connecting the second checkvalve to the tank, a displacement cylinder connected with the tubebetween the check valves, the cylinder having a piston therein to movewater outwardly of the dispensing means, and means to move the pistoninto the cylinder at a rate to cause pressure in the tube between thecheck valves to rise to a sufficient magnitude to close both of thevalves and to move the piston out of the cylinder at a rate to causepressure in the tube between the check valves to be sufliciently low tocause the second check valve to close again, whereby cooling of thecylinder, the piston, the dispensing means, and the tube between thecheck valves by cooler water in the other leg thereof below the checkvalve is prevented.

As stated previously, several other new and improved component parts mayalso be employed to advantage in accordance with the present invention.One of these is a fluid flow control device including a float operatedcheck valve, or a gravity operated check valve.

, According to a feature of the present invention, the fluid flowcontrol device or check valve for the insulated tube may include acylindrical pipe having a lower internal cavity of a predetermineddiameter, a middle internal cavity of a second predetermined diametergreater than said first predetermined diameter, and an annular shoulderat the upper end of the lower internal cavity, a cylindrical floatextending downwardly in the lower internal cavity into the middleinternal cavity. The average density of the float is less than that offluid in the pipe section. A disc-shaped flange having a diameter lessthan the second predetermined diameter and greater than the firstpredetermined diameter is then fixed to the upper end of the float inthe middle internal cavity in a plane approximately perpendicular to theaxis of the float to seat on the shoulder when pressure above the floatexceeds the pressure below the float by a predetermined value. Stopmeans to limit movement of the disc-shaped flange on the float upwardlyin the middle internal cavity beyond a predetermined distance from theshoulder is also provided. The stop means may comprise a spider fixed tothe pipe section internally thereof above the discshaped flange. A pinis then fixed to the disc-shaped float at the center thereof in aposition extending downwardly in the pipe section to limit the upwardvertical movement of the float therein.

According to still another feature of the present invention, a fluidflow control device or check valve for the leg of the tube not insulatedmay include that described in the paragraph immediately preceding withthe exception that an annular flange is provided extending radiallyinward at the upper end of the middle internal cavity, and an upperinternal cavity is provided above the annular flange having a thirdpredetermined diameter less than the annular flange inside diameter, theannular flange inside diameter also being less than the secondpredetermined diameter. A spider assembly is then provided in the upperinternal cavity, the spider assembly including a spider slidablevertically in the upper internal cavity and having an outside diametergreater than the annular flange inside diameter to rest thereon, thespider assembly also including a projection fixed centrally with thespider extending downwardly into the middle internal cavity to hold thedisc-shaped flange on the float in spaced relation to the annular flangewhen the spider rests thereon, the spider assembly having an averagedensity greater than that of the fluid.

The above-described and other advantages of the present invention willbe better understood from the following description considered inconnection with the accompanying drawings.

In the drawings which are to be regarded as merely ililustrative:

PEG. 1 is a diagrammatic view of hot water dispensing apparatusconstructed in accordance with the present invention;

FIG. 2 is an enlarged longitudinal sectional view of one of two valvesillustrated in FIG. 1;

FIG. 3 is a transverse sectional view taken on the line 3-3 of the valveshown in FIG. 2;

FIG. 4 is a broken away longitudinal sectional view of the other of thetwo valves illustrated in FIG. 1; and

FIG. 5 is a perspective view partly in section of a float employed inboth of the valves illustrated in FIGS. 2 and 4.

In the drawing in FIG. 1, water is supplied to the sys tem by means of aconduit 10 which enters a reservoir 11. Conduit 10 may be a water pipeor conduit from any pressurized supply. At the end of conduit 10, avalve 12 is positioned in a manner such that an arm 13 operates thesame, arm 13 having a float 14 connected to one end thereof to be buoyedin water indicated at 15 in reservoid 11. Reservoir 11 has two otherconnections thereto, one being an output pipe 16 connected to a watertank 17 and a standpipe 18 also connected to water tank 17 as a safetymeasure to prevent a high pressure building up in the system in theevent the pipe 16 becomes plugged. It is to be noted that the sides ofreservoir 11 extend upwardly above the entire remainder of the apparatusdisclosed in the system, whereby the water level at 15 may exceed theheighth of any part in the remainder of the system to supply waterthereto under pressure via pipe 16. In other words, a pressure head isprovided by the level of water at 15 above the remainder of the systemto maintain all the component parts of the system clclimpletely full ofwater and the conduits to and from t em.

Water in tank 17 is heated by means of a heating element 19 locatedinternally of tank 17, heating element 19 being supplied with electricpower by a power supply 20 having an automatic control thereof by athermostat 21 to maintain the temperature of the water in tank 17 at asubstantially constant temperature, for example, at about 200 F.

Tank 17 has a substantially U-shaped tube 22 or plumbing systemconnected thereto, an input leg 23 being connected to tank 17 having anopening at 24 therein adjacent to the bottom thereof. U-shaped tube 22is also provided with an output leg 25 having an opening in tank 17located at 26 near the top thereof at one side, opening 24 of leg 23being near the center of the tank 17 adjacent to heating element 19.Location of lower end 24 of input leg 23 near the bottom of the tank 17and adjacent heating element 19 causes water entering leg 24 to be at atemperature higher than that escaping from leg 25 at its lower end 26.In addition to the fact that hot water in leg 23 rises and cold water inleg 24 falls, as will be described in greater detail hereinafter, thelocation of the lower ends 24 and 26 of legs 23 and 25, respectively, intank 17 also facilitates circulation of water in inverted U-shaped tube22.

Insulation indicated at 27 is provided around substantially all thewater-carrying structures connected with tube 22 from tank 17 at theconnection of leg 23 to the position of a check valve 28 connected inleg 25. Fortions 30 of leg 25 from check valve 28 to its lower end 26indicated at 29 are left bare. Hence, water will cool at a substantiallyfaster rate in portions 30 of leg 25 than in other portions of U-shapedtube 22 or other structure connected therewith. For this reason, thewater in portions 36 of leg 25 will become heavier than that in leg 23and water will circulate in tube 22 as long as valve 28 is open, as wellas a check valve located in leg 23.

Although valves 28 and 29 are very similar, they are difierent in onerespect. Valve 29 closes when pressure above it in leg 23 exceeds apressure below it by a predetermined amount. Valve 29 never closes whenthe pressure below it in leg 23 exceeds the pressure above it. On theother hand, valve 28 in leg 25 closes when pressure above the valveexceeds the pressure below it by a predetermined amount and vice versa,i.e., the valve 23 also closes when the pressure in leg 25 below itexceeds the pressure in leg 25 above it.

A dispensing valve assembly 31 is located in the topmost portion 32 ofthe U-shaped tube 22, valve assembly 31 including a housing 33 inside ofwhich a dispensing cylinder 34 is movable vertically against the forceof a helically coiled spring 35. A frusto-conical surface comprising avalve seat 36 is located at the bottom of cylinder 34. A valve 37 isfixed to the upper end of housing 33, the seat 36 being movable withcylinder 34 upwardly in housing 33 to permit the escape of hot waterbetween valve 37 and valve seat 36 onto or through coffee grounds, in asuitable container, not shown. Cylinder 34 is moved upwardly by means ofa fixed connection with a linkage 38 which is moved upwardly by anarmature 39 of a solenoid 46 having a ground connection to a lead 41 atthe output of a timer 42 and a second lead 43 connected from timer 42thereto.

Also connected in top portion 32 of U-shaped tube 22 is a cylinder 44having a piston 45 movable vertically therein on a piston rod 46. Piston45 is normally biased to the position shown in FIG. 1 by means of ahelically coiled spring 47. Piston rod 46 is movable with a link 48fixed thereto which in turn is moved vertically upward by a connectionwith an armature 49 of a solenoid 5i). Solenoid 59 is also connected toground lead 41 of timer 42 and also to timer 42 by a lead 51 thereto.Timer 42 is provided with a push button 52 to initiate the operation ofsolenoids 40 and 50 simultaneously or successively.

The operation of the system illustrated in FIG. 1 is as follows: Wateris supplied by conduit and float 14 operates valve 12 to maintain waterlevel above the remainder of the system. Water is supplied through pipe16 to tank 17, the latter being watertight. Vent 18 is provided simplyfor safety reasons and is generally not involved in the operation of thesystem. Water in tank 17 is heated by heating element 19 operated fromthermostat 21 and power supply 2(). later circulates upwardly in leg 23of U-shaped tube 22 through valve 29 which remains open because a pin 53therein fixed relative to a housing 54 thereof prevents a float 55therein from scaling 011 an internal bore 56. Hot water is circulated upin leg 23, across top portion 32 and downwardly in leg 25 of U-shapedmember 22, all of the same being insulated at 27. Water also circulatesdownwardly through valve 28. Circulation is created by the difference inheat loss of leg 23 and the portions 31) of leg 25 inducing a greaterdensity of water in portions 30 of leg 25 than in leg 23. Valve 28closes when very small diflerential pressure exists across it in eitherdirection; however, the differential pressure created by the differentdensities of the water in legs 23 and 25 is insufli-cient to close thevalve. Hence, hot water flows through leg 25 downwardly through portions30 into tank 17.

When push button 52 of timer 42 is depressed, the opening of solenoid 40is actuated to dispense water from the valve assembly 31 andsimultaneously therewith or immediately thereafter solenoid is operatedto cause piston 45 to rise in cylinder 44 and therefore displace watertherein and cause water to flow out of the valve assembly 31. Under thiscondition, the pressure in U-shaped tube 22 above valves 28 and 29increases rapidly and to such an extent that both of the valves close.The travel of piston 45 in cylinder 44 may be the entire length of thecylinder or some portion thereof fixed by any convenient means. In thepresent case, timer 42 simply de-energizes solenoid 50 after apredetermined length of time as well as solenoid 40. Solenoid 40alternatively may be energized at a time immediately preceding the timethat solenoid 50 is de-energized. Upon de-energization of the solenoids,the action of spring 47 rapidly draws piston 45 back to the piston shownin solid lines in FIG. 1, pressure below atmospheric being created inthe cylinder 44 and therefore in U-shaped tube 22 above valves 28 and29. In this case, although valve 29 stays open because pin 53 limitsmovement of float upwardly in bore 56, valve 28 actually does close. Itis in tact a feature of the invention that this valve closes in thisevent, whereby the withdrawal of water from portions 30 of leg 25 intoU-shaped tube 22 above valve 28 is prevented, the same therebyincreasing the warming efficiency of U-shaped tube 22 and the structureassociated or connected therewith, including valve assembly 31, cylinder44 and piston 45.

Detaiis of the valves 28 and 2? are illustrated in FIGS. 2, 3, 4 and 5.Valve 29 is illustrated in FIG. 2 including a fitting 57 threaded into ahousing 58, and an O-ring 59 provided therebetween. A spider assembly 66is located in the lower end of fitting 57 to support a stop pin 61therein, stop pin 61 being welded to a spider 62 which in turn is weldedto an internal bore 63 in fitting 57. Fitting 57 is provided with aflange at 64 having a bore 65 therein to permit the flow of fluid ineither direction through fitting 57. Pin 61 prevents a float indicatedat 66 from rising further in housing 58 than the dotted line positionshown at 67. This means that fluid can flow in either direction aroundfloat 66 provided pressure above float 66 is not sufllcient to cause thevalve 29 to close. However, as can be seen in the system of FIG. 1,water never generally flows downwardly in valve 29. The flow of water invalve 29 when float 66 is in the position indicated at 67 is upwardlybetween float 66 and lower and middle internal cavities 68 and 69 of thevalve, and upwardly into an upper internal cavity thereof defined bybore 63 over the top of float 66 through the bore 65 of flange 64.

Float 66 is provided with a cylindrical body portion 79 having radiallyprojecting flange 71 fixed to or made integral with its upper endproviding a valve to seat on a valve seat or shoulder 72 of housing 58when the pressure above valve 29 exceeds the pressure therebelow asviewed in FIGS. 1 and 2.

Valve 29 is a float operated valve. For this reason, for the valve toremain open, the average density of the float 66 must be less than thatof the medium in which it is used, namely water in the case of FIG. 1.This is the reason the valve 66 normally occupies the position indicatedin dotted lines at 67 when it is located in leg 23 illustrated in FIG. 1and piston 45 is not moved by solenoid 5t) upwardly in cylinder 44 toincrease the pressure in leg 23 above valve 29.

As shown in FIG. 3, spider 60 is made up of curved pieces of coppersheet material indicated at 73 welded both at points 74 and 75 to pin 61and bore 63 of fitting 57, respectively. Float 66 is also indicated inFIG. 5 and as can be seen may be made of a piece of plastic material ona lathe or molded with flange 71 integral with cylindrical portions 70.The bore 76 of cylindrical portion 76 may be drilled. A plastic disc 77may be press 7 fit into the lower end of float 66 as and cemented inthat position.

An upper portion of valve 28 is shown in FIG. 4., the lower portionthereof being identical to the lower portion of valve 29 shown in FIG.2. As a matter of fact, all of the structure shown in FIG. 4 may beidentical to that illustrated in FIG. 2 with the exception that welds atthe points 75 'are not provided, whereby the spider 78 therein may movevertically from the position shown therein to the position indicated indotted lines at 79. Spider 78 which is fixed to .pin 53 simply providesa weight which is movable.

As stated previously, the construction of valve 28 otherwise may beidentical to that of valve 29. In particular, fittings 80 and 57 may beidentical as well as O-rings 81 and 59. The same is true for spiders 78and 60 as well as housings 54 and 58 and floats 55 and 66.

Float 55 is shown in solid lines in FIG. 4 in a closed shown in FIG.

position having a flange 84 fixed to or integral with its upper end inengagement with a shoulder or valve Seat 85 inside body 54. Valve 28closes when float 55 is in the position shown in solid lines upon themovement of piston 45 upwardly in cylinder 44 to dispense water fromvalve assembly 31. When piston 45 is moved downwardly in cylinder 44 todraw more water from tank 17 via input leg 23 of U-shaped tube 22, float55 moves to the dotted line position indicated at 86 in FIG. 4 andthereby closes a bore 87 of a flange 88 fixed to the lower end offitting 80 by engagement of flange 84 therewith.

When piston 45 is not moving in cylinder 44 and water is circulating inU-shaped tube 22 upwardly in leg 23 and downwardly in leg 25, float 55is maintained in a position not shown in FIG. 4. This position isassumed by the upper end of flange 84 abutting the lower end of pin 53in the position shown in solid lines in FIG. 4. In this regard, it is tobe noted that spider 78 and pin 53 are prevented from falling insidehousing 54 or inside bore 56 of fitting 80 farther than flange 88because the outer edges of spider 78 rest on flange 88. The buoyancy offloat '55 is less than the weight of spider 78 and pin 53. That is,under the conditions stated, i.e., piston 45 does not move, the upperend of flange 84 abuts the lower end of pin 53 in the position shown insolid lines in FIG. 4. It will be appreciated that valve 28 is not onlya float operated valve, but also a gravity operated valve.

From the foregoing, it will be appreciated that the present inventionovercomes the disadvantages of the prior art by avoiding the use of acomplicated valve system and centrifugal pump to circulate water inU-shaped tube 22. In accordance with the present invention insulatingleg 23 and bare portions 30 of leg 25 causes hot water to circulate byvirtue of the increased density of the water in portions 30 of leg 25relative to the water in leg 23.

Still further, a striking advantage of the apparatus of the invention isthat for a constant water temperature in tank 17, circulation in theU-shaped tube 22 increases as the ambient temperature decreases becausethe water in portions 38 of leg 25 becomes still heavier to increase thediflerential circulation pressure. Hence, in accordance with theapparatus of the present invention, compensation for low and changingambient temtemperatures is made automatically to keep the waterdispensing valve 31, the U-shaped tube 22 other than at portions 30 andother structures associated with, connected with, or positioned adjacentportions of U-shaped tube 22 other than portions 30 thereof of leg 25 ata substantially constant and at a relatively high temperatureindependent of ambient temperature.

Still further, the lower end of the leg 23 terminates at 24 adjacent thelower central portion of tank 17 adjacent heating element 19 whereas leg25 terminates at 26 at the upper portion on the side of tank 17 toincrease the differential circulation pressure.

In addition to the foregoing features, another is also provided in thatvalve 28 closes when the difierential pressure thereacross exceeds apredetermined amount regardless of on which side of the valve thepressure is highest. This means that when piston 45 moves downwardly incylinder 44, colder water in portions 30 of leg 25 will not be drawn upinto U-shaped tube 22 or cylinder 44 when cylinder 44 fills.

Another outstanding feature of the invention is the use of theparticular valves 28 and 29 of the construc tions illustrated in FIGS.2, 3, 4 and 5. These valves are extremely sensitive and accuratealthough the valve 28 will not close in response to the differentialpressure creased by the relatively high heat transfer rate of theportions 30 of leg 25 not insulated relative to that in those portionsof U-shaped tube 22 insulated at 27. Nevertheless, neither of the valves28 or 29 are operated electrically.

Note will be taken that water in tank 17 adjacent the lower end 24 ofleg 23 will be warmer than water in tank 17 at the lower end 26 of leg25. This is true because heating element 19 is simply placed closer toend 24 than it is to end 26. Thus, if all the insulation shown in FIG. 1were removed, the Water in leg 25 would be cooler than the water in leg23. This would therefore cause a moderate flow of water to heat thedispensing valve assembly 31.

Although only one specific embodiment of the system of the invention hasbeen described and illustrated, it is to be expressly understood thatthe invention is by no means limited to the embodiment selected to be sodescribed and illustrated. Many changes and modifications of theinvention will of course suggest themselves to those skilled in the art.Thus, the invention is defined only in the appended claims.

What is claimed is:

1. Hot water dispensing apparatus comprising: a tank; an invertedU-shaped tube having downwardly extending legs connected to said tank atdifferent corresponding positions; dispensing means connected with saidtube at the top thereof between said legs; a first check valve in one ofsaid legs, said first check valve being adapted to close when thepressure in a portion of said one leg between said first check valve andsaid dispensing means is greater than that in a portion of said one legbetween said first check valve and said tank; a second check valve inthe other of said legs, said second check valve being adapted to closewhen the pressure in said other leg thereabove exceeds that in saidother leg therebelow by a predetermined amount; a cylinder between saidcheck valves, said cylinder having a piston therein to move wateroutwardly of said dispensing means; and means to move said piston intosaid cylinder at a rate to cause pressure in said tube between saidcheck valves to rise to a magnitude sufficient to close both of saidvalves.

2. Hot water dispensing apparatus comprising: a tank; an invertedU-shaped tube having downwardly extending legs connected to said tank atdifferent corresponding positions; dispensing means connected with saidtube at the top thereof between said legs; a first check valve in one ofsaid legs, said first check valve being adapted to close when thepressure in a portion of said one leg between said first check valve andsaid dispensing means is greater than that in a portion of said one legbetween said first check valve and said tank; a second check valve inthe other of said legs, said second check valve being adapted to closewhen the pressure in said other leg thereabove exceeds that in saidother leg therebelow by a predetermined amount; a cylinder between saidcheck valves, said cylinder 'having a piston therein to move wateroutwardly of said dispensing means; means to move said piston into saidcylinder at a rate to cause pressure in said tube between said checkvalves to rise to a magnitude sufficient to close both of said valves;and means to maintain Water in said tube and in said tank underpressure.

3. Hot water dispensing apparatus comprising: a tank; an invertedU-shaped tube having downwardly extending legs connected to said tank atdifferent correspond ing positions; dispensing means connected with saidtube at the top thereof between said legs; a first check valve in one ofsaid legs, said first check valve being adapted to close when pressurein a portion of said one leg between said tirst check valve and saiddispensing means is greater than that in a portion of said one legbetween said first check valve and said tank; a second check valve inthe other of said legs, said second check valve being adapted to closewhen differential of pressures across it are of predetermined magnitudesregardless of whether or not the water pressure thereabove in said otherleg is higher or lower than the water pressure there'below in said otherleg; greater insulation on said one of said legs than on the other, saidlegs having openings into said tank surrounded by water, said openingsbeing located in positions such that water surrounding said one leg iswarmer than water surrounding said other leg; means to heat said tank; adisplacement cylinder connected with said tube between said checkvalves, said cylinder having a piston therein to move water outwardly ofsaid dispensing means; and means to move said piston into said cylinderat a rate to cause pressure in said tube between said check valves torise to a magnitude suificient to close both of said valves and to movesaid piston out of said cylinder at a rate to cause pressure in saidtube between said check valves to be sufficiently low to cause saidsecond check valve to close again, whereby cooling of said cylinder,said piston, said dispensing means, and said tube between said checkvalves by cooler water in said other leg thereof below said check valveis prevented.

4. Hot water dispensing apparatus comprising: a tank; an invertedU-shaped tube having downwardly extending legs connected to said tank atditferent corresponding positions, one of said legs having an opening insaid tank near the bottom thereof and the other of said legs having anopening in said tank near the top thereof; dispensing means connectedwith said tube at the top thereof between said legs; a first check valvein one of said legs, said first check valve being adapted to close whenpressure in a portion of said one leg between said first check valve andsaid dispensing means is greater than that in a portion of said one legbetween said first check valve and said tank; a second check valve inthe other of said legs, said second check valve being adapted to closewhen differential pressures across it are of predetermined magnitudesregardless of whether or not the Water pressure thereabove in said otherleg is higher or lower than the water pressure therebelow in said otherleg; greater insulation on said one of said legs than on the other, saidlegs having openings into said tank surrounded by water, said openingsbeing located in positions such that water surrounding said one leg iswarmer than water surrounding said other leg;

means to heat the bottom of said tank; a displacement cylinder connectedwith said tube between said check valves, said cylinder having a pistontherein to move water outwardly of said dispensing means; means to movesaid piston into said cylinder at a rate to cause pressure in said tubebetween said check valves to rise to a magnitude sufiicient to closeboth of said valves and to move said piston out of said cylinder at arate to cause pressure in said tube between said check valves to besufficiently low to cause said second check valve to close again,whereby cooling of said cylinder, said piston, said dispensing means,and said tube between said check valves by cooler Water in said otherleg thereof below said check valve is prevented; and means to maintainwater in said tube and in said tank under pressure.

5. Hot water dispensing apparatus comprising: a tank; an invertedU-shaped tube having downwardly extending legs connected to said tank atdifferent corresponding positions; dispensing means connected with saidtube at the top thereof between said legs; a first check valve in one ofsaid legs, said first check valve being adapted to close when pressurein a portion of said one leg between said first check valve and saiddispensing means is greater than that in a portion of said one legbetween said first check valve and said tank; a second check valve inthe other of said legs, said second check valve being adapted to closewhen differential of pressures across it are of predetermined magnitudesregardless of whether or not the water pressure thereabove in said otherleg is higher or lower than the water pressure there-below in said otherleg; greater insulation on said one of said legs than on the other, saidlegs having openings into said tank surrounded by water, said openingsbeing located in positions such that water surrounding said one leg iswarmer than water surrounding said other leg; means to heat said tank; adisplacement cylinder connected with said tube between said checkvalves, said cylinder having a piston therein to move water outwardly ofsaid dispensing means; means to move said piston into said cylinder at arate to cause pressure in said tube between said check valves to rise toa magnitude sufiicient to close both of said valves and to move saidpiston out of said cylinder at a rate to cause pressure in said tubebetween said check valves to be sutficiently low to cause said secondcheck valve to close again, whereby cooling of said cylinder, saidpiston, said dispensing means, and said tube between said check valvesby cooler water in said other leg thereof below said check valve isprevented; and means to maintain water in said tube and in said tankunder pressure.

References Cited by the Examiner UNITED STATES PATENTS 1,141,243 6/15Foster 239 X 1,758,984 5/30 Stricker 239139 X 2,079,898 5/37 Burchenal222146 2,123,604 7/38 Johnson 239-128 X RAPHAEL M. LUPO, PrimaryExaminer.

1. HOT WATER DISPENSING APPARATUS COMPRISING: A TANK; AN INVERTEDU-SHAPED TUBE HAVING DOWNWARDLY EXTENDING LEGS CONNECTED TO SAID TANK ATDIFFERENT CORRESPONDING POSITIONS; DISPENSING MEANS CONNECTED WITH SAIDTUBE AT THE TOP THEREOF BETWEEN SAID LEGS; A FIRST CHECK VALVE IN ONE OFSAID LEGS, SAID FIRST CHECK VALVE BEING ADAPTED TO CLOSE WHEN THEPRESSURE IN A PORTION OF SAID ONE LEG BETWEEN SAID FIRST CHECK VALVE ANDSAID DISPENSING MEANS IS GREATER THAN THAT IN A PORTION OF SAID ONE LEGBETWEEN SAID FIRST CHECK VALVE AND SAID TANK; A SECOND CHECK VALVE INTHE OTHER OF SAID LEGS, SAID SECOND CHECK VALVE BEING ADAPTED TO CLOSEWHEN THE PRESSURE IN SAID OTHER LEG THEREABOVE EXCEEDS THAT IN SAIDOTHER LEG THEREBELOW BY A PREDETERMINED AMOUNT; A CYLINDER BETWEEN SAIDCHECK VALVES, SAID CYLINDER HAVING A PISTON THEREIN TO MOVE WATEROUTWARDLY OF SAID DISPENSING MEANS; AND MEANS TO MOVE SAID PISTON INTOSAID CYLINDER AT A RATE TO CAUSE PRESSURE IN SAID TUBE BETWEEN SAIDCHECK VALVES TO RISE TO A MAGNITUDE SUFFICIENT TO CLOSE BOTH OF SAIDVALVES.